Biometry, age classes and sex ratio in Magellanic Penguins (<i>Spheniscus magellanicus</i>) stranded on the northwest coast of the province of Río Negro (Argentina)
Biometry, age classes and sex ratio in Magellanic Penguins (Spheniscus magellanicus) stranded on the northwest coast of the province of Río Negro (Argentina)
Centro de Investigación Aplicada y Transferencia Tecnológica en Recursos Marinos Almirante Storni (CIMAS) – CONICET. Güemes 1030, R8520CXV, San Antonio Oeste, Argentina
Patricio J. Pereyra
Centro de Investigación Aplicada y Transferencia Tecnológica en Recursos Marinos Almirante Storni (CIMAS) – CONICET. Güemes 1030, R8520CXV, San Antonio Oeste, Argentina
Juan Pablo Seco Pon
Instituto de Investigaciones Marinas y Costeras (IIMyC), Facultad de Ciencias Exactas y Naturales, Universidad Nacional de Mar del Plata – CONICET. Av. Juan B Justo 2550, B7608FBY, Mar del Plata, Argentina
Argentina Bahía de San Antonio Protected Natural Area beached birds penguins San Matías Gulf seabirds
How to Cite
Pizá, Victoria M., Patricio J. Pereyra, and Juan Pablo Seco Pon. 2025. “Biometry, Age Classes and Sex Ratio in Magellanic Penguins (Spheniscus Magellanicus) Stranded on the Northwest Coast of the Province of Río Negro (Argentina)”. El Hornero 40 (1): 61-72. https://doi.org/10.56178/eh.v40i1.1510.
The Magellanic Penguin (Spheniscus magellanicus) is a diving seabird that breeds on islands and coasts of Chile and Argentina, including the Malvinas Islands. The discovery of beached seabirds on the coasts is a phenomenon that occurs regularly. Throughout the year, it is common to observe individuals of the species on the northwest coast of Río Negro Province. The general objective of this study is to report the biometrics, sex ratio and age classes of dead Magellanic Penguins found beached on the coasts of the Bahía de San Antonio Protected Natural Area. From June 2020 to June 2022, systematic sampling of beached birds was carried out at two sites and was complemented with opportunistic reports. A total of 288 dead beached Magellanic Penguins were recorded, and 51 randomly selected individuals were analyzed. Most of the specimens were classified as juveniles and a smaller proportion as adults. The sex ratio was significantly asymmetric, equivalent to a ratio of 3.75 beached females for each male. Juvenile individuals showed significant differences in their biometric measurements, at least with respect to wing length and middle toe length. Our results are in line with previous reports for the species on the coasts of Buenos Aires Province in Argentina and south-central Brazil. This study allows a first characterization of the occurrence of Magellanic Penguin strandings in the study area.
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